Numerous improvements have been made to lathes used in machining crankshafts; see U.S. Pat. Nos. 3,789,709; 3,896,690; 4,261,234; 4,305,689; 4,779,495; and 4,895,057. However, none of the lathes disclosed in the foregoing patents are the type commonly used for rebuilding crab shafts of all types and sizes. A common problem exists for all such lathes during the rebuilding of crab shafts used for internal combustion engines and compressors. Because the crank journals or cranking are offset from the main longitudinal axis of the crankshaft, the crankshaft must be positioned in the lathe so that the crankshaft moves in a circular rotary path. Consequently, the crankshaft must be readjusted and reclamped for each new offset or stroke position of the crankshaft. Each reclamping position requires time-consuming steps before the crankshaft is ready for machining.
The procedure involved to process various crankshaft journals using a typical prior art shop lathe are set forth below.
One example of such a typical prior art shop lathe suitable for regrinding an eight foot locomotive crankshaft, type V-16, having a twelve inch stroke, is Model K 2700 manufactured by AMC-Schou of Nordhavnsgade, Denmark. The thirty one steps required to set up the main journals of this machine are as follows:
(1) Engage manual locking pin on headstock to position chuck slide in vertical position. PA1 (2) Loosen hand knob lock(s) on chuck slide. PA1 (3) Set headstock chuck slide on zero stroke by rotating lead screw. PA1 (4) Tighten headstock slide locking hand knob(s). PA1 (5) Loosen headstock counterweight locking knob(s). PA1 (6) Position headstock counterweight to minimum offset position by rotating lead screw. PA1 (7) Tighten headstock counterweight locking hand knob(s). PA1 (8) Engage manual locking pin on tailstock to position chuck slide in vertical position. PA1 (9) Loosen hand knob lock(s) on tailstock chuck slide. PA1 (10) Set tailstock chuck slide on zero stroke by rotating lead screw. PA1 (11) Tighten tailstock slide locking hand knob(s). PA1 (12) Loosen tailstock counterweight locking hand knob(s). PA1 (13) Position tailstock counterweight to minimum offset position by rotating lead screw. PA1 (14) Tighten tailstock counterweight locking hand knob(s). PA1 (15) Hoist crankshaft into loading position. PA1 (16) Adjust headstock chuck to receive snout of crankshaft. PA1 (17) Adjust tailstock chuck to receive flange of crankshaft. PA1 (18) Move tailstock into position and lock. PA1 (19) Tighten tailstock chuck. PA1 (20) Tighten headstock chuck. PA1 (21) Disengage tailstock locking pin. PA1 (22) Disengage headstock locking pin. PA1 (23) Proceed to grind or weld appropriate main journal and thrust surfaces. PA1 (24) Engage headstock locking pin. PA1 (25) Engage tailstock locking pin. PA1 (26) Support crankshaft with hoist. PA1 (27) Loosen headstock chuck. PA1 (28) Loosen tailstock chuck. PA1 (29) Loosen tailstock lock. PA1 (30) Back off tailstock. PA1 (31) Remove crankshaft. PA1 (1) Loosen headstock chuck slide locking knob(s). PA1 (2) Elevate headstock chuck slide block to proper stroke position indicated on scale by rotating leadscrew. PA1 (3) Tighten headstock chuck slide locking knob(s). PA1 (4) Loosen tailstock chuck slide locking knob(s). PA1 (5) Elevate tailstock chuck slide block to proper stroke position indicated on scale by rotating leadscrew. PA1 (6) Tighten tailstock chuck slide locking knob(s). PA1 (7) Using hoist, position crankshaft snout into headstock chuck. PA1 (8) Position crankshaft flange to fit into tailstock chuck. PA1 (9) Move tailstock forward. PA1 (10) Tighten headstock chuck. PA1 (11) Tighten tailstock chuck. PA1 (12) Tighten tailstock lock. PA1 (13) Loosen tailstock chuck locking knob. PA1 (14) Loosen headstock chuck locking knob. PA1 (15) Rotate crankshaft until proper degree position is obtained. PA1 (16) Tighten headstock chuck locking knob. PA1 (17) Tighten tailstock chuck locking knob. PA1 (18) Disengage tailstock locking pin. PA1 (19) Disengage headstock locking pin. PA1 (20) Loosen headstock counterweight locking knob(s). PA1 (21) Adjust headstock counterweight by turning leadscrew to half the balance position. PA1 (22) Disengage tailstock locking pin. PA1 (23) Loosen tailstock counterweight locking knob(s). PA1 (24) Adjust tailstock counterweight by turning leadscrew to hold the balance position. PA1 (25) Tighten tailstock counterweight lock knob(s). PA1 (26) Weld or grind connecting rod journal. PA1 (27) Engage headstock locking pin. PA1 (28) Engage tailstock locking pin. PA1 (29) Loosen tailstock chuck locking knob. PA1 (30) Loosen headstock chuck locking knob. PA1 (31) Rotate next connecting rod to proper degree position. PA1 (32) Tighten headstock chuck locking knob. PA1 (33) Tighten tailstock chuck locking knob. PA1 (34) Repeat steps (28)-(33) seven more times (equals 42 steps) until all connecting rod journals are processed. PA1 (77) Engage headstock locking pin. PA1 (78) Engage tailstock locking pin. PA1 (79) Support crankshaft with hoist. PA1 (80) Loosen headstock chuck jaws. PA1 (81) Loosen tailstock chuck jaws. PA1 (82) Loosen tailstock lock. PA1 (83) Back tailstock away. PA1 (84) Remove crankshaft. PA1 (a) headstock and tailstock slide blocks having guide rails and bushings distal the respective main spindle shafts and journalled on the headstock and tailstock mini-shafts; PA1 (b) headstock and tailstock slideways, or slides, fixedly attached to the respective main spindle shafts and mounted within the guide rails of the respective slide blocks, each slide having a locking pin detent; PA1 (c) headstock and tailstock locking pins removably positioned in each of the respective locking pin detents for locking the slides in a horizontal crankshaft loading position; PA1 (d) headstock and tailstock pinion gear racks fixedly attached to the respective slides; PA1 (e) headstock and tailstock pinion gears engaging the respective pinion gear racks and fixedly attached to the ends of the respective mini-shafts proximate the respective dog collars that are fastened to the respective chuck back plates and journalled on the mini-shafts; and PA1 (f) headstock and tailstock slide block locking means operably mounted on and for locking each of the respective slide blocks along the respective slides after the desired crankshaft lathe stroke setting has been determined. PA1 (1) Allows an operator to more rapidly position or set the offset crankshaft rod bearing journals and to align them properly along the main spindle shaft longitudinal axis; PA1 (2) Allows one to more easily determine the stroke position, i.e. determining when the rod journal is concentric with the longitudinal axis of the main shaft, of the rod journal to be reground or otherwise machined, by simply rotating the crankshaft; PA1 (3) Is of simple, rugged construction of proven design; and PA1 (4) Allows one to deposit a uniform weld that does not require as much regrinding.
The eighty four additional steps required to set up the eight rod journals of this same machine are as follows:
Many complex pieces of equipment are available to accomplish the goal of setting the stroke on crankshaft lathes used to carry out repetitive machining of series-manufactured, special workpieces; see U.S. Pat. No. 4,297,926. However, for the average crankshaft rebuilding shop such pieces of equipment are too complex and costly and are not required for non-repetitive machining. The present invention provides the shop operator with a simple, inexpensive device or system for adding to existing lathes to overcome the problem of simultaneously and more efficiently setting the stroke position of the crankshaft.